Oysters Don’t Have Ears But Still Use Sound to Choose Their Homes

Oyster larvae find their homes by responding to the unique sounds of a reef.

When they venture away from their oyster bed, young oysters float along in the ocean currents, only able to move up and down within the water column. Eventually, while still in the larval stage, they attach to a reef or sediment. But how do they know where to land?

Oysters don’t have feet, Lewis Carroll pointed out in “The Walrus and the Carpenter,” and they don’t have ears either. But as NC State grad student Ashlee Lillis found, in a paper published in the journal PLOS One, oyster larvae find their homes by responding to the unique sounds of an oyster bed or reef.

The oysters, she and her colleagues write, sense the vibrations of the sound in the water column and using those vibrations as guideposts towards their new homes. Lillis and co. used recordings of reefs to test their theory in the lab, and both in the lab and in the wild, the oysters responded to the reef sounds, settling more when exposed to recordings of the reef itself, as opposed to recordings of areas further away.

“The ocean has different soundscapes, just like on land,” Lillis says in a press release. “Living in a reef is like living in a busy urban area: there are a lot of residents, a lot of activity and a lot of noise. By comparison, the seafloor is more like living in the quiet countryside.” Lillis hopes to figure out what soundscapes are unique to healthy reefs, and using that information to either monitor the health of oyster beds or help establish new oyster beds.

The lab at NC State also has a gallery of soundscapes where you can hear the popcorn-like crackle of the reefs for yourself.

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